Shots in the Back - Are they "Legal"?
An Explanation for Self-defense
 © 2018 by Gary Marbut, Expert - Use of Force

The Question

Rarely, there is a self defense shooting where the assailant presents with entrance wounds in the back, yet the defender is certain that he or she used force justifiably to stop a real threat to the defender's life.  How can this be explained, and how may it be demonstrated to a jury if needed?

This scenario is better documented in law enforcement shootings, but is far from unknown in non-law enforcement defensive shootings.

The Incident

In 2016 I was engaged as an expert in a criminal case in which a homeowner (let’s call him Smith) was charged with homicide for having shot an intruder (let’s call him Jones) in Smith's home.  It was my job to explain to the jury how the homeowner could have been justified in the use of lethal force when the intruder died (offsite) from a bullet that made an entrance wound in the intruder’s back.

The short version of my reconstruction of the incident is that the armed homeowner knew there was an intruder in the house who had made a forcible entry (indication of criminal intent with potential for violence).  The armed homeowner entered his home, searched for the intruder, and encountered the intruder at a distance of about ten feet upon stepping into the doorway of a room in the house.  The intruder made a sudden move that the homeowner interpreted as an assault, but which was the beginning of a spin towards a large window that the intruder had opened as an escape route.  When the intruder made the sudden move, the homeowner discharged a round from his 9mm pistol, a round that connected with the intruder as he spun away from the encounter.  The intruder died nearby from a bullet wound that had entered the intruder's back.

The homeowner was charged with homicide and claimed self defense.

How could I explain to uninformed members of the jury and to the court, with serious credibility, that Smith could have used lethal force correctly, even though the fatal entrance wound was in the Jones’s back?  At that point the intruder was apparently trying to escape and no longer threatening the homeowner with serious bodily injury or loss of life, the usual criteria in law for use of lethal force in self-defense.  For a vivid demonstration for the jury, I had to actually test this scenario, with appropriate timing, with live ammunition, at a shooting range.  I had to video and document the tests for my expert report in this case and in preparation for my testimony before Smith's jury.

What follows is extracted from my expert report, albeit with the names changed for privacy reasons.


As an expert and as a very interested person, one of the information sources I attend to is the Force Science Institute (FSI) and the Force Science Research Center located at Mankato State College in Mankato, Minnesota.  I read and collect the regular and informative FSI newsletters.  The FSI has done groundbreaking research, mostly in a law enforcement context, about use of force issues.  One aspect of use of force that FSI has researched is the timing of an encounter that justifies a response of lethal force.  Some aspects about the mechanics and human physiology of that combination have long been known.  Some remained to be discovered or demonstrated through testing by FSI.

We've long known that there is some time lag between an external stimulus to human action, and the resulting action itself.  Although the timing can be different with an audible stimulus and a visible stimulus, let us discuss a visual stimulus.  For a person to respond to a visual stimulus, several serial (sequential) things must happen.

First, the person must look at and see the visual environment.  That is, the person must see whatever the stimulus may be and that visual image must be registered by the photoreceptor cells of the retina, transmitted to the optic nerve, and transported to the brain.  That happens quickly, but it does take time.  Let's suppose that the test stimulus is a light changing from green to red, and let’s identify the time it takes to get that image to the brain as the "apprehension time."

Then, the brain must interpret the image.  That is, the brain must figure out "Hey, there was a green light shining but it went out and now there's a red light shining."  That happens quickly, but it also takes time.  We might call this the "interpretation time."

Next, the brain must figure out what the information means and decide what to do with the information.  It could take days or weeks before any decision is made about what to do with visually received information (e.g., responding to a letter).  Or, there could be an urgent, pre-planned response, such as "Send a signal to the leg to stomp the foot on a simulated brake pedal."  Still, an analysis must be conducted about what to do with the information, and a decision must be made before any response is possible.  No matter how well pre-planned, this process also takes time.  It takes longer with an unanticipated stimulus.  Let's call this the "decision-making time."

Then, the brain must send the signal out to the parts of the body necessary to carry out any instructions from the brain in response to the initial stimulus.  And, the nervous system must carry the impulses to the correct parts of the body for action.  For example, maybe the brain must send a coordinated instruction to all the muscles of the right leg and right foot for the foot to lift, move over, and stomp down on a simulated brake pedal.  It will take time to formulate and send that complex set of signals, and for the signals to travel to the necessary body parts.  Call this the "instruction time."

Finally, the necessary body parts must get into action and actually follow out the instructions sent out over the neural links by the brain.  Of course, that takes time too.  Call this the " performance time."

Each of these steps can usually be completed in a fraction of a second, but these fractions necessarily add up.  Adding up the apprehension time, the interpretation time, the decision-making time, the instruction time, and the performance time cannot be eliminated, although with training and practice it can be reduced.  People with decent vision and reflexes will usually take most of a second to complete this process, at best.  When we're young, we will be quicker.  As we age, this process takes more time.  All of this has been studied and measured.

It has also been measured exactly how long it takes a bad guy to snatch a concealed firearm from a waistband and fire a fatal shot.

The law enforcement world has long said, "Action beats reaction."  That is a recognition that the amount of time it takes a bad guy to snatch and fire a gun is less time (quicker) than the time it takes an officer to recognize the evolving threat and respond effectively.

It was the FSI that first put all of this together scientifically and documented what experienced officers already knew, but documented in valid experiments conducted by professionals and published in peer-reviewed papers in professional publications.

What FSI learned and documented is that, if an officer is faced with a potentially hostile bad guy and the bad guy makes a sudden move (a "furtive move"), the officer dares not wait to see what might evolve out of the move.  If the officer waits until he sees a gun emerge from the bad guy's waistband, the officer is likely dead.  It's simply too late at that point for the officer to draw his own gun and fire before being seriously wounded by the bad guy.

That's why a smart police officer may already have drawn his firearm.  That's why a smart police officer will instruct the suspect to "move VERY SLOWLY."  That's why a surviving police officer will take cover if possible and fire his pistol if he sees a sudden movement.

FSI also documented another phenomenon known by experienced cops but difficult to explain, also a timing issue.  Not only can a bad guy snatch a gun and kill an unprepared officer before the officer can respond, but the same bad guy can also spin 180 degrees just as quickly.  Here's where understanding the timing becomes important.

Imagine this.  Imagine a police officer (or a non-police defender) is confronting a bad guy.  Sensibly, the cop has his gun drawn, pointing at the bad guy.  The cop issues the command to "Freeze!"  Upon that command, the bad guy makes a sudden and violent movement.  In order to live to go home to his family, the cop makes the immediate decision that the movement could be a physical assault to capture the officer's gun, or it could be the bad guy snatching his own gun.  After a one-third or one-half second of processing, the cop's brain dispatches the signal down his neural pathways to his trigger finger telling his finger to contract on the trigger of his pistol.

This signal is just racing past the cop's elbow when the visual images coming into the cop's brain begin to suggest that the bad guy is not actually attacking, but is in the process of spinning around, maybe to escape.  About the time that the signal to fire passes the cop's wrist, his brain gets around to sending a follow-up signal to the trigger finger to NOT contract.  This signal to NOT fire must follow the same pathway as the signal TO fire just did, at the same speed.  By the time the message to NOT fire is clearing past the brain stem at the base of the brain, the signal TO fire clears the knuckles and is contracting the muscles of the trigger finger.  When the officer's firearm discharges, the signal to NOT fire is still somewhere near the officer's shoulder, flashing its way to intercept the trigger finger contraction.

While this is going on, the bad guy has spun 180 degrees, and the officer's bullet enters the bad guy's back.  This has happened many times.  Finally, FSI brought the science of human neurophysiology to the issue to explain how this can happen, and does happen.

The reader is referred to:

AN EXAMINATION OF POLICE OFFICER MENTAL CHRONOMETRY:  “I SWEAR...I DON’T KNOW HOW I SHOT HIM IN THE BACK”, by Jeffrey B. Bumgarner, Ph.D., Texas Christian University, William J. Lewinski, Ph.D., Minnesota State University, William Hudson, Ph.D., Minnesota State University, Sgt. Craig Sapp, Tempe Police Department, done for the Journal of The Association for Crime Scene Reconstruction, 2006 (LINK).

Force Science News 91.
Force Science News 92.

So, is there an explanation for how in the Smith incident the entrance wound in Jones could be in the back, but Smith could still have used lethal force in an allowable manner?  Yes.

Imagine this.  Both actors in this drama were psychologically jacked up and totally on edge.  Both were probably pumped full of adrenaline.

Jones knew he was engaged in criminal activity, activity for which there would be a high price to pay if he were caught.  He was a burglar.  It is likely that he saw and/or heard Smith drive up and get out of his vehicle.  He may have seen that Smith was armed.  When Smith entered the house through Jones's point of forcible entry (front door), he inadvertently blocked Jones's primary escape route.  According to Smith, he observed Jones try to get to the back door in the kitchen, but when Smith issued the verbal command to "Stop," Jones bolted instead.  Now Jones was trapped, and he knew he was.  By that point, Jones was in overdrive and red-lined.  It has been learned since that Jones swore that he would never go back to prison.  With the knowledge that Smith was armed, that put Jones in a literal life-and-death situation, on life-and-death overdrive.

Smith entered his home knowing that some person was inside committing a felony-level crime.  The strange car was still outside and the front door was kicked in.  In the kitchen, Smith had his first encounter with Jones.  Jones was larger, stronger, younger, and probably faster than Smith.  Smith would have known that, if it came to unarmed combat, Jones would have a considerable advantage, a serious disparity of force.  Also, for practical and proper tactical reasons, Smith must assume that Jones would in no way limit his criminality to felony burglary.  Rather, to be tactically sound, Smith must assume that Jones would be willing to maim or kill in order to avoid interdiction or capture.  Plus, Jones had articulated to Smith, "I'm going to hurt you."  So, Smith was also ramped up psychologically, also in overdrive.

It was while both were in this absolutely hyper state that they had their final confrontation at a distance of about two or three yards.  Jones came into Smith's view because Smith moved into a position where he could see Jones, not because Jones moved into Smith's view.  The layout of the house dictates this.

In this totally hyper state for both, Smith moves into a position where Jones is visible.  For a fraction of a second, both freeze.  At that point, Jones makes a sudden move.  Smith's brain registers that sudden movement and his brain interprets it as "I'm being attacked," an essential and tactically correct decision if he wants to survive.  Smith's brain sends the signal to his arms and hands to raise his pistol and squeeze the trigger.

That signal is racing down Smith's neural pathways.  As with the example above, the signal to raise the pistol and fire is just passing Smith's elbow when his eyes and optic nerve begin getting information to his brain that Jones may not be attacking, but may be spinning around.  About the time the signal to fire the pistol is passing Smith's wrist, his brain sends out a follow-up message to the hands and finger to NOT shoot.  But, it's just too late for that second signal to catch up with the first.  The first shoot signal gets to Smith's hand and the pistol fires.  At this point Jones has spun nearly 180 degrees and the bullet enters Jones's back.

So, was Smith justified in applying lethal force?  Yes.  At the moment the decision to fire was made and the message was sent by the brain, Smith was in fear for his life from a known criminal, younger, larger, and stronger, who was trapped with no obvious route of escape and desperate to avoid capture.

It is not Smith's fault that Jones triggered Smith's decision with a sudden movement.  That was Jones's mistake.  It is not Smith's fault that Jones's sudden move turned out to be the beginning of a spin and not an attack.  That sudden move was Jones's mistake.  And, it is not Smith's fault that Jones could turn faster than Smith could send the recall signal.  That is just human neurophysiology, as has been demonstrated scientifically.

A known phenomenon

This phenomenon of timing with a quickly turning assailant is a well known subject in the world of those who specialize in self defense, including self defense instructors, self defense experts, and self defense attorneys.  However, it is not generally known among the public, and often not known among police officers and prosecutors.

In the book, Deadly Force: Understanding Your Right to Self Defense (Gun Digest Books, 2014), by Massad Ayoob and Jeff Weiner, in the chapter "Shot in the back" the authors say:

This turning and shooting factor was later quantified in peer-reviewed literature by Dr. Bill Lewinski, head of the Force Science Institute, and still later rediscovered and quantified by Dr. Martin Fackler and one of his associates at the International Wound Ballistics Association, in the 1990s.  I documented it on film in 2001 for the ALI-ABA in a CLE (Continuing Legal Education for attorneys) training film on management of deadly force cases.  ALI is the American Law Institute, the "blue chip provider" of CLE training material, and the ABA is the American Bar Association.  It remains in the archives of ALI-ABA in their CLE-TV series.  It was documented on film again in 2012, including live fire demonstrations on turning targets, for "Personal Defense TV" on the Sportsman Channel, available in their archives as well.

AN EXAMINATION OF POLICE OFFICER MENTAL CHRONOMETRY:  “I SWEAR...I DON’T KNOW HOW I SHOT HIM IN THE BACK”, by Jeffrey B. Bumgarner, Ph.D., Texas Christian University, William J. Lewinski, Ph.D., Minnesota State University, William Hudson, Ph.D., Minnesota State University, Sgt. Craig Sapp, Tempe Police Department, done for the Journal of The Association for Crime Scene Reconstruction, 2006, (See Appendix for full article).

This article reports the findings of a 4-experiment study involving 102 police officers in a major police department in the Southwestern United States.  The results of the study demonstrate that many variables go into an officer’s ability to react to stimuli in a timely manner and that even in laboratory conditions, there is ample time for the threat picture to change before an officer can either turn on, or turn off, a decision to react by firing a weapon.

Tobin and Fackler (20) conducted a study which measured the reaction times of officers in firing drawn sidearms (but with finger outside of trigger guard as per the standard police practice) in response to stimuli, and compared those measurements with the time it takes for a person to turn their torsos away (90 and 180 degrees) from officers after posing a threat. ... They found that the average individual can turn his or her torso 90 degrees in 0.31 seconds and 180 degrees in 0.676 seconds. In other words, in the time it took an officer with a drawn firearm to fire his or her weapon at a threat, the suspect could already have turned 180 degrees away from the officer at the moment of discharge.

A corollary to the plain implications of the time measurements is the difficulty an officer (or any human being) has in “turning off” a reactionary decision made in the moment. In a shooting situation, once an officer decides to shoot at a suspect in response to some threatening stimulus, it is nearly impossible to abort that decision

In fact, the physical and psychological limitations of the human condition do not apply only to law enforcement officers. Detectives called to the scene of a “routine” shooting incident between two civilians may wish to not-so-readily dismiss the claim of the suspect that the victim had posed a threat, despite entry bullet wounds in the victim’s back. Obviously, consideration of reaction time doesn’t explain all shootings. Common sense, eye-witness testimony, and physical evidence tend to close the cases. But in those instances when common sense suggests the suspect’s innocence while the victim’s wounds suggest the suspect’s guilt, innocence may still be an option. (Emphasis added.)

Testing the phenomenon

I determined to test this phenomenon for myself.  A piece of shooting range equipment I manufacture causes a target to rotate through 180 degrees.  I mounted a 3D mannequin target on one of my units, and dressed the dummy in a clean T-Shirt.

3D mannequin target mounted on turning operator

I took a video of this unit, at 30 frames per second, rotating the target so I could play it back one frame at a time, count the frames from beginning of the turn to end of the turn, and thereby get an accurate time for the turning of this device.  I also took a video of myself turning quickly, for the same purpose.  I learned that the turning target speed and my turning speed were effectively the same (20 frames or 0.66 seconds), which agrees exactly with the Tobin and Fackler study cited by Ayoob above.  I assumed this would be so because it was an intentional design feature of the equipment I manufacture, but I captured the video of both just to prove the similarity in turning speed and to have the proof available as needed.

Then, I took this unit and my video camera (Canon VIXIA HF R300) to the Deer Creek Shooting Center to test some other subjects and their ability to engage this turning target.  I set up for the shooters to shoot from seven yards from the target.

Test layout
Setup for turning target testing

I captured data from a total of ten shooters of various experience levels, ages, gender, and backgrounds.  All test subjects had some experience and training.  Some had a lot.

I had each shooter try the challenge beginning in three different starting positions.  These three starting positions were:

1.  "Sighted in" - pistol in a two-handed grip, pistol held at eye level, sights on the target;

Sighted in
Demonstration of "sighted in" position by the author

2.  "Low ready" - pistol in a two-handed grip, pistol held at abdomen level, pointed down range (the classic "search position");

Low Ready
 Demonstration of "low ready" by the author

3.  "At side" - pistol in a one-handed grip, held at side pointing 45 degrees down.

At side
Demonstration of pistol at side by the author

In each position, the shooter had the pistol in this condition:  Magazine inserted, chamber loaded, safety off, not decocked, finger off the trigger and on the pistol frame above the trigger guard.  For this make and model of pistol, this condition of the pistol is the one in which the pistol is most quickly ready to fire - it only needs the trigger pressed with a light, single-action stroke to fire.

According to my reconstruction of the incident, my interviews, and in my judgment, the low ready position used is the most similar to Smith's position at the moment of encounter.

Smith was moving through the house.  It is very difficult to walk, maintain balance, and hold a gun up at eye level with two hands.  That would make the sighted in position less than likely.  However, given the tenseness of the situation, I doubt that Smith would have had the pistol down by his side.  Those reasons, in part, explain why the low ready position, or some variation of that, would best simulate Smith's condition at the time of the incident.

Other "ready" positions.  There are other "ready" positions that may be used in this sort of situation, some made popular through movies and television, and some that are taught by competent trainers.  One is "high ready," which has the pistol held in a two handed hold and about four to six inches below eye level, barrel horizontal, muzzle pointed straight down range.  Another is a sort of movie port arms, another two-handed hold on the pistol, but with the pistol held at the shooter's forehead level, muzzle up, and off-center to the side to allow the shooter to see around the hands and pistol.  Another is the small-town-cop low ready, also a two-handed hold, arms straight with elbows locked, with the pistol held below waist level, and with the muzzle pointed down just in front of the shooter's feet.  Perhaps the last is a professional chest-ready, with the pistol at chest level, held tight against the chest, held firmly in the dominant hand and the non-trigger fingers of the non-dominant hand cradled into the web of the thumb and index finger of the support hand, with the muzzle of the pistol pointed down and forward of the feet.

There was simply not time available to test all of these various ready positions in the test needed for this situation.  And, all of these other ready positions are essentially the same in time-to-shot as the low ready position tested.  If a shooter must move a pistol from some ready position and into a sighted-in position to take an accurate shot, the time-in-transit for the pistol from the ready position to the shooting position will be one of the shorter parts of the whole process, and will be about the same from all mentioned ready positions.

The pistol used by all of my volunteer test subjects was an exact twin to the one used in and recovered from the Smith incident.  The only difference is the serial number.

Pistol used in test
Pistol from the incident on left; pistol used in tests on right.

About this Star 9mm pistol, and just for background, there are a surprising number of conditions in which this pistol can be kept.  This Star has an exposed hammer and a combined safety and decocking lever.  The decocking lever brings the hammer to rest in the forward position.  The safety moves the rear of the firing pin forward of the rear face of the firing pin stop, making it impossible for the hammer to contact the firing pin.  Other than those, this pistol's features are standard for a self-loading pistol.  Here are the various conditions in which this pistol can be kept:

1.  Empty with no magazine in the pistol and no round in the chamber.

2.  A loaded magazine in the magazine well, no round in the chamber, and the safety in the no-fire position.  (The consequence of the safety being in the no-fire position is that if the slide is racked to transfer a round of ammunition from the magazine to the chamber, the pistol still will not fire.)

3.  A loaded magazine in the magazine well, no round in the chamber, and the safety in the fire position.  (The consequence of the safety being in the fire position is that if the slide is racked to transfer a round of ammunition from the magazine to the chamber, the pistol will then fire if the trigger is pressed.)

4.  A loaded magazine in the magazine well, a round in the chamber, the safety in the no-fire position and the hammer decocked.  In this condition, a long, double-action pull will cycle the trigger and hammer, but will not fire the pistol because with the safety in the no-fire position the firing pin is held forward of the firing pin stop, inaccessible by the hammer.

5.  A loaded magazine in the magazine well, a round in the chamber, the safety in the no-fire position, and the hammer cocked.  In this condition, a light, single-action trigger pull will drop the hammer from the cocked position, but it won't fire the pistol because with the safety in the no-fire position the firing pin is held forward of the firing pin stop, inaccessible by the hammer.

6.  A loaded magazine in the magazine well, a round in the chamber, the safety in the fire position and the hammer decocked.  In this condition, a long, double-action pull will cycle the trigger and hammer, and fire the pistol.

7.  A loaded magazine in the magazine well, a round in the chamber, the safety in the fire position and the hammer cocked.  In this condition, a short, single-action pull will fire the pistol.

It is believed that condition #7 above is the condition the Smith pistol was in at the time of the confrontation in the Smith home.  This is the condition in which the pistol may be most quickly fired.  Any of the other conditions would take longer to fire than #7.  Because of that, it is the condition for the pistol used by volunteers in the tests.  Volunteers were instructed to begin with their trigger finger on the frame, above the trigger and trigger guard, but not on the trigger, a standard firearm safety practice.

The test subjects were told that as soon as they detected movement from the mannequin target, they should fire one shot at the center of mass (center of chest) of the target.  When the subjects started at the low ready, all subjects raised the pistol to eye level before firing.  When they started with hand at side, most raised the pistol into a two-hand grip at eye level before firing, although a few fired with only one hand on the pistol.

Test results

While I believe some version of the classic low ready/search position is the one Smith found himself in at the moment of final encounter with the intruder, I tested all three of the positions listed above.  To score the test shooters, I examined the mannequin after each shot to determine the angle of bullet passage through the mannequin.  I scored each shot according to whether the mannequin was fully facing the test shooter, 1/4 of a turn away, 1/2 of a turn away, 3/4 turned away, or fully turned away from the test shooter when the bullet passed through the mannequin.  After each shot, I put a square of white tape over any entrance and exit holes so the bullet path would be obvious for subsequent shots.  The result of the testing was:

1.  Sighted in.  None of the volunteers were able to trigger a shot while the front of the target was facing them.  Four of ten triggered a shot when the target was 1/4 turned away.  Five of ten triggered a shot when the target was 1/2 turned away.  One of ten triggered a shot when the target was 3/4 turned away.

2.  Low ready (the assumed position of Smith during the incident).  Ten out of ten volunteers tested made their shot after the turning target had fully turned away.

3.  Pistol at side.  Ten out of ten volunteers tested made their shot after the turning target had fully turned away.

It is no surprise that those volunteers who were able to trigger a shot when the target was only 1/4 turned, and only from the sighted-in position, were the more experienced shooters.  Those included one Army veteran recently returned from multiple tours in Iraq and Afghanistan, and a competitive pistol shooter with years of experience in the sport of practical pistol (a sport that develops and requires speed and accuracy with handguns).

For a target turning at the same speed I can turn (a 68 year old male), and with the test subjects starting in the most likely start position, the low ready "search position," ALL of those tested shot the mannequin in the back.  That is, the mannequin had spun a full 180 degrees by the time EVERY person tested fired their single shot.  That's 10 out of 10 tested subjects got hits on the back of the turning dummy target when shooting as quickly as possible, triggered by sudden movement.  Three of the subjects shoot competitively in the sport of practical pistol, all subjects had some firearms training, and one was a recent Iraq veteran.  All volunteers were recruited at a shooting range, so all had some interest in firearms just to be present and available for recruitment and this test.  I'd say all members this group of test subjects probably had skills and abilities at least equal to Smith's, and probably superior to his.

See the attached videos of my test subjects shooting.  In compiling and editing these videos, some things were done to make them more understandable by the viewer.  Included first are a few seconds of each test subject engaging the turning mannequin at real time speed - unedited except for clipping the segment from longer periods of non-relevant activity.  However, this happens so quickly for each shooter that it's difficult to see exactly when the shot breaks in relation to the turning mannequin.  So, for each test subject, the shot was also repeated with a short, slow motion clip including when the actual shot was fired.  And, in the slow motion repeat the clip was paused briefly at the exact moment that the gunshot broke, so the viewer can see the extent to which the mannequin was turned at the instant of the shot.

Thanks to Ty Marbut for the video editing and production.

Low ready video

Pointed down video

Pointed in video



In final answer to this question, yes, there is a perfectly reasonable explanation, even if not obvious, for why the entrance wound in Jones can be in the back and Smith can still be accepted to have used lethal force in a justifiable manner.  I have documented, explained, and demonstrated that reason in the testing performed, recorded, and described here.


About the author:  Gary Marbut is accepted in state and federal courts as an expert concerning self-defense, use of force, firearm safety, and related topics.  Gary is the author of Gun Laws of Montana, now in its Fifth Printing.  He is a veteran firearms instructor, manufactures shooting range equipment for law enforcement agencies nationwide, is president of the Montana Shooting Sports Association, and competes in two different shooting disciplines.